Process of preparing metallic salts of dithiocarbamic acid



Patented June 9,v 1925.

UNITED, -STATES- 1,541,433 PATENT OFFICE.

AsUJuRo NIKAIDO, or: BAY CITY, MICHIGAN, AssrGNoR 'ro 'MICHIGANCHEMICAL company, A CORPORATION OF MICHIGAN.

PROCESS OF PREPARING- METALLIC SALTS OF DITHIQCARBAMIC ACID.

No ,Dlfawing,

lated compounds.

In United States Patent 1,465,677 to Molony' and Nikaido August 2-1, 1923 there is described amino-ammonium salts. of'

dithiocarbamlc acid, such as the amino-am,- monium salt of monomethyl and dimethyl dithiocarbamic acid, wherein beet sugar residue is utilized as one ofthe reacting materials. These salts, characterized ,by avery disagreeable odor, are exceedingly unstable, affording 'a comparatively small yield, about one percent of the weight ofthe beet sugar residue used.

I have found that a stable compound, affording a yield of approximately six per cent by weight of the beet sugar residue used may be produced if the dithiocarbamic compounds are in the form of metallic salts.

The production of the metallic salts of dithiocarbamic acid utilizing as one of the reacting materials the impure gases derived from the distillation of beet sugar, residue involves several difficulties. The present invention is designed to overcome the same.

I have found that the amino-ammonium salts of dithiocarbamic acid derived from' the treatment of beet sugar residue with carbon bisulfid'contain ammonium sulfid,-

ammonium hydrate, ammonium sulphocyanate and possibly other undesirable ammom 2 s SNHz(CHa)z The filtrate resulting from the precipitation of the zinc. salts contains a considerable amount of amine-hydrosulfate. The amines Application filed August 9,1921. Serial No. 491,042.

monium compounds. If a'zinc salt. is added directly to the amino-ammonium salts ofdithiocarbamicacid a considerable amount of .zinc sulfid and hydroxid are formed which render the resulting salt of dithiocar bamic acid exceedingly impure. I have'ascertained that. a pure salt may be obtained by acidifying the 'dithiocarbamic acid solu-' tion with a weak acid before the addition of the zinc salt. Strong acids, such as mineral acids, cannot be used, since they decompose the "amino-ammonium salts of "dithiocarbamic acid. Acetic acid has been found satisfactory. I .have alsofound that unless the dithiocarbamiccacid solution is considerablydiluted' the precipitate formed upon the addition of the zinc salt will be'lumpy causing considerable loss in filtration. A diluted solution gives, upon the addition of metallic salt, a granular precipitate which is easily filtered. A 5% solution has given good results. i After the amino-ammonium salt-solution of dithiocarbamic acid has been diluted and acidified with a weak acid, a solution of a zinc salt, preferably zinc sulfate, is added thereto. A 10% solution of the zinc sulfate is preferred, this dilution givin a precipitate admitting of eflicient filtration;

The zinc salts formed are separated from the mother-liquor by centrifuging, and are more): 1 4 W W) H2 4 S 2 2 recovery of the amines from thezinc. filtrate materially increases the yield of the zinc dithiocarbamic compound. v

An analysis of the 1 precipitate formed during one of the runs gave the following: Monomethyl 'dithiocarbamate of zinc 16.98% Dimethyl dithiocarbamate of zine 75.19

Balance impurities and moisture.

Themetallic salts produced are a mono- 2 7 La iness methyl dithiocarbamate and dimethyl dithiocarbamate of the metal, or a mixture of the two. These compounds have the following formulas: I

Nnon more): cs 3 cs sM' sM' monomethyl dimethyl dithiocarbamate dithiocarbamate Other metallic salts of these acids, such as iron, mercury and lead, may be made in a similar manner.

,I claim:

1. The process of producing stable metallic salts of alkyl dithiocarbamic acid comprising passing the distillation-product formed by the destructive distillation of beet sugar residue into carbon bisulfid, separating therefrom a solution of the aminoammonium salts of dithiocarbamic acid, acidifying the solution with a weak acid, adding a metal salt thereto, and recovering therefrom the metallic salts of dithiocarbamic acid.

2. The process of producing stable zinc salts of alkyl dithiocarbamic acid comprising passing the distillation-product formed by the destructive distillation of beet sugar residue into carbon bisulfid, separating therefrom a solution of the amino-ammonium salts of dithiocarbamic acid, acidifying the solution with a weak acid, adding a zinc salt thereto, and recovering therefrom the zinc salts of alkyl dithiocarbamic acid.

3. llhe process of producing stable zinc salts of methylated dithiocarbamic acid comprising passing the distillation-product formed by the destructive distillation of beet sugar residue into carbon bisulfid, separating therefrom a solutionof the aminoammonium salts of dithiocarbamic acid, acidifying the solution with a weak acid, adding a zinc salt thereto, and recovering therefrom the zinc salts of methylated dithiocarbamic.

4. The process of producing stable metallic salts of alkyl dithiocarbamic compounds comprising passing the distillation-product formed by the destructive distillation of beet sugar residue into carbon bisulfid, sepalrating therefrom a solution of the aminoammonium salts of ditlriocarbamic acid, di-

luting the solution, acidifving the solution I ing the same into carbon bisulfid for the formation of additional amino salts' of dithiocarbamic acid, treating the latter with a metallic salt, and recovering the metallic salts of dithiocarbamic acid.

6. The process of producing stable metallic salts of alkyl dithiocarbamic acid comprising passing the distillation-product formed by the destructive distillation .of

beet sugar residue into carbon bisulfid, separating therefrom a solution of the aminoammonium salts of d'ithiocarbamic acid, acidifying the solution with a weak acid, adding a metal salt thereto to precipitate the metallic salts of dithiocarbamic acid, separating the precipitate from the filtrate and recovering the amines present in the filtrate for further use in the process. 7 The process of producing stable metallic salts of alkyl dithiocarbamic acid comprising passing the distillation-product formed by the destructive distillation of beet sugar residue into carbon disulfid, separatlng therefrom a solution of the amino-ammonium salts of dithiocarbamic acid, adding a metal salt theretoto precepitate the metallic salts of dithiocarbamic acid, separating the precipitate from the filtrate and recovering the amines present in the filtrate for further use in the process.

In testimony whereof, I have hereunto subscribed my name this 20th day of July 1921.

YASUJURO NIKA-IDO.

Witnesses:

'- WARRENWE. CARTER,

EDWIN 0'. LIST. 

